Flash Flooding and Hail in Texas, September 16, 2001

TEXAS/OKLAHOMA PANHANDLES FORECAST DISCUSSION...CORRECTION
NATIONAL WEATHER SERVICE AMARILLO TX
225 PM CDT SUN SEP 16 2001

CORRECTED THE PRELIM CCF TEMPERATURES FOR TUESDAY AND TUESDAY NIGHT

THE FORECAST CHALLENGE THIS RUN SHOULD BE PINPOINTING HOW WIDESPREAD
AND WHERE AREAS OF PRECIPITATION WILL OCCUR OVER THE NEXT 48 HOURS.
SURFACE ANALYSIS SHOWED A NEARLY STATIONARY AND POORLY DEFINED COLD
FRONT STRETCHING FROM EASTERN COLORADO SOUTHEAST THROUGH THE EASTERN
TEXAS PANHANDLE. AT UPPER-LEVELS...A SHORTWAVE OVER THE FAR EASTERN
TEXAS PANHANDLE WILL EXIT THE REGION TONIGHT WITH WEAK RIDGING IN ITS
WAKE. EXPECT SCATTERED CONVECTION BY LATE THIS AFTERNOON INITIATING
OFF THE MOUNTAINS AS A RESULT OF HEATING. THIS CONVECTION SHOULD
INCREASE IN COVERAGE ALONG THE INSTABILITY AXIS ACROSS THE
NORTHWESTERN ZONES TONIGHT. HOWEVER...THE CONVECTION THIS MORNING
OVER THE EASTERN ZONES MAY MAKE IT HARD FOR THE EASTERN ZONES TO
RECOVER LATE THIS AFTERNOON...LIMITING WIDESPREAD CONVECTION THERE
TONIGHT. AFTER A BREAK EARLY MONDAY...SHORTWAVE ENERGY WILL INCREASE
MONDAY AFTERNOON AS DISTURBANCES PUSH ACROSS COLORADO AND NEW MEXICO.
LIFT ASSOCIATED WITH THESE FEATURES SHOULD ALLOW MORE WIDESPREAD
CONVECTION TO DEVELOP ESPECIALLY NORTH OF A FRONT SITUATED OVER THE
NORTHERN ZONES MONDAY AFTERNOON. AS INSTABILITY MAXIMIZES ALONG AND
SOUTH OF THE FRONT AND A STRONG LOW-LEVEL JET DEVELOPS JUST TO THE
EAST MONDAY EVENING...STRONG CONVECTION MAY INITIATE ESPECIALLY IF
THE SHORTWAVE PHASES WITH THE PARAMETERS AT LOWER-LEVELS. EXPECT THE
MOST WIDESPREAD STORMS IN THE NORTHEAST EXTENDING WEST ALONG THE
FRONT. AFTER POTENTIALLY HEAVY RAIN...STRATIFORM RAIN SHOULD FOLLOW
LATE MONDAY NIGHT WITH SOME CLEARING TUESDAY AS THE SHORTWAVE EXITS.
THE COLD FRONT SHOULD BE WELL SOUTH OF THE FORECAST AREA BY TUESDAY
MORNING WITH COOLER TEMPERATURES TO FOLLOW TUESDAY AND TUESDAY
NIGHT.

FOR LATER PERIODS...SURFACE HIGH PRESSURE WILL BEGIN BUILDING INTO
THE CENTRAL ROCKIES TUESDAY AND TUESDAY NIGHT AS A LARGE UPPER-
LEVEL TROUGH BEGINS TO EXIT THE REGION. NORTHWEST FLOW BEHIND THE
TROUGH MAY ALLOW POST-FRONTAL SHOWERS OR STORMS TO DEVELOP ACROSS
THE FORECAST AREA TUESDAY NIGHT. AS THE WHOLE SYSTEM EXITS
WEDNESDAY...SHOWERS SHOULD DECREASE AND COOL SURFACE HIGH PRESSURE
SHOULD SETTLE IN OVER THE SOUTHERN PLAINS. AS A RESULT...COOLER
TEMPERATURES ARE EXPECTED WEDNESDAY AND WEDNESDAY NIGHT. TOWARD THE
END OF THE WEEK...MEDIUM RANGE MODELS INDICATE THAT A RIDGE WILL
BUILD IN ACROSS THE SOUTHERN STATES THURSDAY. THIS MAY RESULT IN
DRIER CONDITIONS AND WARMER TEMPERATURES AS WE APPROACH THE WEEKEND.

AMA 61/88 58/78 55 435
DHT 58/85 56/76 52 635

.AMA...
TX...NONE.
OK...NONE.

CB

OKZ001>003-TXZ001>020-162100-

TEXAS/OKLAHOMA PANHANDLES THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE AMARILLO TX
100 PM CDT SUN SEP 16 2001

THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE WESTERN
AND CENTRAL TEXAS AND OKLAHOMA PANHANDLES THROUGH TONIGHT.

THE SLIGHT RISK AREA IS MAINLY ALONG AND WEST OF A LINE FROM LIBERAL
KANSAS TO CANYON TEXAS.

SEVERAL SURFACE BOUNDARIES REMAIN ACROSS THE PANHANDLES FROM LAST
NIGHT/S THUNDERSTORMS. THESE BOUNDARIES WILL TEAM UP WITH SURFACE
AND MID LEVEL MOISTURE AND DAYTIME HEATING TO PRODUCE THUNDERSTORMS
THIS AFTERNOON INTO TONIGHT. AN UPPER AIR DISTURBANCE WILL MOVE
TOWARD THE PANHANDLES THIS EVENING AND WILL PROVIDE INSTABILITY
ALOFT FOR THUNDERSTORMS TO CONTINUE.

A COLD POOL OF AIR ALOFT OVER THE SOUTHERN ROCKIES WILL SLOWLY
SPREAD INTO THE WESTERN AND CENTRAL PARTS OF THE PANHANDLES.  THE
COLD AIR ALOFT WILL HELP IN THE DEVELOPMENT OF HAIL AND DOWNBURST
WINDS IN THE STORMS.

HEAVY RAIN...WHICH COULD CAUSE FLASH FLOODING...IS ALSO A THREAT
FROM THESE STORMS TONIGHT AS THEY WILL HAVE PLENTY OF MOISTURE TO
WORK WITH. MANY PLACES IN THE NORTHWEST TEXAS PANHANDLE AND THE
CENTRAL OKLAHOMA PANHANDLE RECEIVED 1.5 TO 2.5 INCHES OF RAIN LAST
NIGHT. ANY MORE RAIN ON THE ALREADY SATURATED GROUND WILL ONLY
AGGRAVATE THE FLOODING POTENTIAL.

SPOTTERS AND EMERGENCY MANAGEMENT OFFICIALS ACROSS THE SLIGHT
RISK AREA SHOULD REMAIN ALERT FOR POSSIBLE ACTIVATION THIS AFTERNOON
OR EVENING.

GOEHRING